The present invention relates to a transmission line technique and more particularly to a transmission line applicable for different frequency bands using the same wiring pattern, as well as an optical module using the transmission line as an electric signal feed line for feeding an electric signal to a laser diode or an optical modulator and a method of manufacturing the optical module.
In the optical communication field, transmission/reception data tend to become higher in bit rate every year with advanced computerization. Also as to the laser module for the transmission of an optical signal with use of an optical modulator, in order to transmit a high bit rate optical signal in the state where there is no error from a transmission side to a reception side, it is essentially necessary to improve high frequency characteristics of a high frequency transmission line which transmits an electric signal to the optical module. For example, in a package including a modulator integrated laser diode, a wide band is attained by connecting a terminal resistance and an optical modulator in parallel with each other, connecting a wire inductance and an impedance matching resistance with one grounded and the other in series with the said parallel connection, and connecting a high-frequency transmission line to an opposite end of the impedance matching resistance (see, for example, Japanese Patent Laid Open No. 257412/2001 (FIG. 1 and pages 4 to 5)).